A liquid or gel monopropellant thruster consists of a pressurization system, propellant tank, fuel valve, and a catalytic bed reactor with a nozzle. The thruster begins operation when the pressurization system has been activated and the monopropellant is pressurized in the propellant tank. When the fuel valve opens, the pressurized monopropellant is expelled into the catalytic bed reactor where the monopropellant is exothermically decomposed into small molecular weight gasses. Hydrazine and hydrazine blends have been considered as monopropellants because of their ability to decompose at ambient conditions on an iridium catalyst to form warm (1000.degree. F. to 1500.degree. F.) gases. Hydrazine is undesirable because of its toxicity and high freezing point (34.degree. F.).